Robo-wheels to help search-and-rescue teams

At times it does make sense to reinvent the wheel — for example, when it comes to getting rescue robots into and out of avalanches. This is what researchers in Japan say, explaining why they have developed an adjustable wheel that can adapt to different kinds of snow conditions.

Duncan Graham-Rowe writes that robots are increasingly used to locate survivors of disasters such as earthquakes, who can be trapped in places too risky for human rescuers. “But few are applicable to rescue in snow,” says Taro Iwamoto at Ryukoku University in Shiga, Japan. Even caterpillar treads can skid or sink in certain types of snow and ice.

Iwamoto’s team has built a wheel with six vanes on its side that are linked to both the wheel and a central hub. The rear of each vane pivots on the wheel, while a spoke from the hub joins the vane nearer its center. By varying the position of the hub relative to the wheel axle, the operator can alter the angle of the vanes, ensuring the best possible traction for the conditions and preventing the wheel from sinking or slipping.

For example, on ice the vanes can be angled so that those underneath hook into the surface to gain traction, pulling the wheel forward. In soft snow, they can either lie flat to compact the snow or act as paddles to push the wheel along. The wheel can also transform into a digging device, allowing the robot to burrow into a wall of snow or simply clear a path. To prevent snow from clogging up the central space between the vanes, the hub control mechanism is housed in the wheel disc.

Noel Sharkey, a roboticist at the University of Sheffield, says initial tests of the device on snow look promising. He thinks the vane mechanism should give it more traction than alternatives such as caterpillar tracks or skis. What is more, robotic vehicles that use it should be able to carry larger payloads. “But I suspect they may be considerably slower,” he says.

Indeed, the current prototype has a maximum speed of twenty centimeters a second, though Iwamoto says the team is designing a four-wheel-drive version that they think will be faster. “We plan to test it this winter,” Iwamoto says.

Robots capable of traveling in snow and ice could play an important role in locating and rescuing people from avalanches, alongside or in place of dogs and human rescuers. They could be especially useful where buildings have been buried, says Benjamin Zweisel of the Swiss Institute for Snow and Avalanche Research in Davos. “It’s not easy to get into buildings. Usually the snow is very compact after an avalanche.”